1. Field of the Invention
The present invention relates to customer premises equipment (CPE) (e.g. a telephone base and receiver unit) for use in telephone subscriber systems and more particularly to a customer premises equipment for use in telephone subscriber systems having caller identification (CID) and call waiting (CW) on a plurality of telephone lines.
2. Background Information
The call-waiting (CW) feature is generally well-known and available on many telephone systems (i.e., central offices). In conventional CW, when a subscriber to the CW service is engaged in a telephone conversation with a second party, the central office notifies the subscriber when a third party is attempting to call the subscriber. Typically, the central office notifies the subscriber of the incoming third party call by providing a CW tone or "click" which is audible to the subscriber. The subscriber then has the option to place the second party on hold and speak to the third party, or to ignore the CW signal and continue speaking to the second party.
Another service offered on some central offices is caller identification (CID). In the conventional CID feature the central office transmits a digitally encoded signal, representing the telephone number of a calling party, to a subscriber's customer premises equipment (CPE) (e.g., a telephone base and receiver unit). Provided that the subscriber's CPE is equipped with the appropriate receiving and decoding circuitry, the subscriber can view the calling party's telephone number on a display device and decide whether or not to answer the telephone call.
Some CPEs permit a subscriber to combine the CW and CID features in a single CPE (for example, CIDCW CPE) whereby the subscriber's CIDCW CPE displays a third party's CID information, (for example, the third party's name, telephone number, and any other information transmitted from the central office) while the subscriber is in communication with a second party. This allows the subscriber to make an informed decision as to whether or not to interrupt a current telephone call with the second party in order to answer the incoming call from the third party.
Some subscribers find it convenient to have access to multiple telephone lines. Although there are various CPEs capable of handling multiple telephone lines, should a subscriber want to implement the CIDCW feature on each of the telephone lines, a separate CIDCW CPE for each of the telephone lines is generally required. Obviously, this can be cumbersome and expensive for the user.
One solution may be to combine the circuitry from multiple CIDCW CPEs under a single housing. If so, the number of circuit elements needed to process CIDCW information for a single telephone line would be multiplied by the number of telephone lines the CPE is capable of handling. That is, for example, a two line CIDCW CPE would have two CID detectors (i.e., a separate CID detector for each telephone line) . Of course, as the number of circuit elements within a CPE are multiplied, the size and cost of the CPE increases. Clearly, there is a need for a cost-effective CPE and method that is capable of detecting, receiving and processing CID information over a plurality of telephone lines.
The CID and CIDCW features are well-known and are described in TR-NWT-000030, Voiceband Data Transmission Interface Generic Requirements, Issue 3 (Bellcore, April 1992) and TR-NWT-000575, CLASS Feature: Calling Identify Delivery on Call Waiting, FSD 01-02-1090, (A module of LSSGR, FR-NWT-000064) Issue 1 (Bellcore, October 1992), plus Revision 1, December 1994, the entire disclosure of each is incorporated herein by reference.